The present invention relates to a bundle count verifier and more particularly to an apparatus and method for determining the deviation in the total number of newspapers or other signatures in the stack from a given standard number.
A bundle count verifier is used in the newspaper industry to verify that the number of newspapers in a stack, which are to be made into a bundle by a strapping machine, has the correct number of newspapers. Before bundling a newspaper, the printed newspaper is folded and the different sections assembled. The final newspaper may have sections made from standard newsprint and a variety of inserts, such as magazine sections and the like printed on different stock paper.
The assembled newspaper is then stacked by a stacking apparatus. After being stacked, the newspapers are then strapped together into bundles. With the exception of designated odd-count bundles, bundles should all contain the same number of newspapers in order to facilitate efficient allocation of the newspapers to distributors. If bundles contain too many newspapers, these excess newspapers represent lost cash to the publisher. If too few newspapers are present in bundles then the distributors will not be able to complete their distribution. This is costly to the publisher since special deliveries have to be made to complete the distribution.
Due to the economies of scale which large publishers operate under, it has been proven economical to install bundle count verifiers to verify that the bundles leaving the stacking apparatus contain the correct number of newspapers. Failure to verify the bundle count while stacking can result in grievous economic consequences after just one run through a malfunctioning stacker.
The newspaper industry does use bundle count verifiers which rely on the weight of the stacks of newspaper. In this system, all stacks of newspapers which weigh the same are considered to have the same number of newspapers. However, due to variations in the newsprint itself, this often is not true. The characteristics of newsprint stock is not constant from one roll to the next and, consequently, the same number of newspapers may have two different weights. One inconsistency in newsprint which affects the weight is the difference in moisture content due to newsprint stock having variable ability to absorb the printing ink. Additionally, the weight may vary because the fibers present in different newsprint stocks may vary themselves (i.e., a variation in fiber density).
A bundle weigher must make thousands of accurate measurements a day in a commercial newspaper setting. Each one of the weight measurements made by the weigher must be highly accurate in order to avoid unnecessary shutdowns due to false indications or malfunctions. An apparatus able to withstand this prolonged wear and tear is expensive to fabricate and can still be susceptible to breakdown.
There are other industries which sell groups of signatures or other flat, stacked articles. For example, magazines, envelopes and sheet materials, are stacked and sold in bundles. These industries have the same motivations for using bundle count verifiers as cited in reference to the newspaper industry. However, alternative types of bundle count verifiers have been proposed which do not rely on the weight of the stack of signatures.
One type of bundle count verifier which has been proposed relies on simply the height of the stack to determine the number of stacked flat articles. One proposed apparatus for implementing this type of bundle count verifier counts the number of flat articles in the stack by positioning a platen onto a stack of corrugated sheets of paper. The platen is driven by a stepping motor. During the period in which the stepping motor is driving the platen, the counter counts. When the platen contacts the top of the stack of corrugated sheets of paper, a contact switch associated with the platen stops the counter and deactivates the stepping motor. This type of device is illustrated in the U.S. Pat. No. 4,417,351 to Williams et al.
It has also been proposed to count stacks of articles by measuring the height of the stacked articles by means of optical detection.
There are also certain inaccuracies associated with these concepts. Using a height measurement without sufficient compression force to verify or count the number of flat articles or signatures in the stack can result in inaccurate operation for certain types of flat articles such as newspapers. These inaccuracies arise because of the variable vertical compressibility of flat articles such as newspapers. When a single height measurement is taken of the stack, the variable compression of the individual articles in the stack cannot be taken into account. The variable compression of newspapers arises from differences in settling within the stack and differences in the way the newspaper is assembled.
Regardless of the disadvantages or advantages found in the bundle count verifiers of the prior art, they all represent investment into an entirely separate piece of machinery. This investment is significant to any business and particularly so to small businesses. In order to minimize investments into new apparatus it is often desirable to incorporate a new capability in an old apparatus.
Another restriction placed on the utilization of bundle count verifiers by small publishers are the small irregular orders which a small business must fill. Not all bundles may have the same number of newspapers. Consequently, it is necessary to provide a means for disabling the bundle count verifier when an odd count stack is being verified. Without this feature odd count bundles would indicate an error to bundle verifiers.